Current tennis rackets come in a wide variety of designs with every racket having a predetermined balance. The performance of the racket is greatly affected by its balance—the weight distribution from head to butt cap. For the purpose of teaching/learning tennis (ranked in the top ten most difficult games to play), a head-heavy balance distribution is highly preferable for ground strokes, while a head-light distribution is preferable for volleys. To date, there is not a racket that allows the flexibility while learning the game to have both head-heavy and head-light in one racket.
With respect to demoing (the period of time before the purchase of a racket, when a player borrows several different rackets from a retail or other source to test before committing to a purchase), the ability to alter the balance of the racket allows the customer to borrow a single racket instead of many that they can adjust to their personal balance preference. A racket can then be finally selected based on the player's preferred balance selection. This narrows the purchasing field from several hundred distinct rackets and brands to just a few, thus drastically reducing the lag time before the purchase of a racket.
For general game play, different weight distributions in a racket accommodate different styles of play. For instance, someone who prefers playing from the baseline, a head-heavy (weight distribution toward the top or the head of the racket) balance might be most appropriate. Conversely, a head-light balance would be more suited to a serve and volley player. In regular game play a player often changes styles of play from point to point for various reasons including exploiting a particular opponent's weakness, or in response to an opponent exploiting their weakness, accommodating different court surfaces, weather conditions, or even personal temperament. The ability to alter the racket balance optimizes the racket for different styles of play from point to point. Creating a head-heavy balance shift can aid in countering headwinds or adding extra power to strokes that might not otherwise be generated. The different court surfaces—for example, clay courts slow down the ball and produce a high bounce, while grass courts are the fastest type of tennis court, and hard courts are considered “medium” surfaces—each favor different styles of play.
To address the singularity of balance within a racket several previous inventions have developed mechanisms, each of which has their own drawbacks. U.S. Pat. No. 6,432,004 B1, for example, proposes an add-on weight system that is pressure fit within the throat of the racket. This mechanism, while allowing for adjustability, interferes with the pre-established aerodynamics of the racket. It also places large amounts of pressure on the frame and provides extra pieces that can dislodge at high speed, and cause injury to a player or spectator. These same disadvantages are present in U.S. Pat. Nos. 4,179,121 and 4,427,195. An early concept for dynamically changing the racket balance during use is taught in U.S. Pat. No. 3,907,292. However, this concept is based on out-of-date racket technology that would not apply to modern constructions. Moreover, this approach is a violation of the ITF definition of a racket (due to the dynamically changing balance).
It is therefore desirable to provide a system that allows the balance of the racket to change while securely maintaining the chosen balance during play. The choice of the change becomes conscious and deliberate, thus educating the player [on the effects of balance] while improving their performance. The mechanism for allowing balance change should be easy to use, not compromise structural integrity of the racket, and maintain the original lines of the racket without protuberances or parts that can be accidentally dislodged. It should, more generally, allow the racket to comply with any applicable rules and regulations of the game.